1. Field of the Invention
The present invention relates to a production method for devices which have chip-on-chip structures or the like in which (for example, two) semiconductor chips are stacked and bonded. In particular, the present invention relates to a production method for devices which can be made very thin by reducing the overall thicknesses of the devices.
2. Description of the Related Art
In recent years, as typified by compact digital devices (for example, mobile phones and digital cameras), various electronic devices have been greatly improved in lightness, thinness, and compactness. In order to achieve this, semiconductor chips and semiconductor package components which have important functions as components are required to be compact and thin. In recent years, a semiconductor device having a chip-on-chip structure in which two or more semiconductor chips are stacked and packaged has been widely used as a device that can be integrated and be made thinner. In particular, instead of a conventional structure in which electrodes are wire-bonded, a structure, in which surfaces of chips face each other and electrodes of electronic circuits formed thereon are directly connected to each other, can be simple and made thinner, thereby being advantageous. For example, semiconductor chips of this type are produced as disclosed in Japanese Unexamined Patent Application Publication No. 2001-196528.
However, these thin devices having a chip-on-chip structure are required to be even thinner. In order to meet this requirement, as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-57404, a technique, in which semiconductor chips stacked on a substrate are ground by a grinding device or the like so as to have desired thicknesses, may be effectively used.
However, when the semiconductor chips, which are stacked on the substrate, are made thinner, there is a limit to the reduction of the overall thickness of the chip-on-chip structures of the semiconductor chips. In addition, it is difficult to make the semiconductor chips thinner while at the same time maintaining the sufficient strength of the semiconductor chips so that no damages (for example, cracking or breakage) occurs therein.